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Strategies for changing the conductivity of Li 2 CO 3 is introduced into the fabrication of Li-CO 2 battery. Benefitting from the favorable hierarchical architecture constructed (CPM-MnO 2), facile charge transfer occurs between catalytic surface and Li 2 CO 3 by –OH⋯O hydrogen bonds improves the metallicity of Li 2 CO 3 , facilitating the formation/decomposition of Li 2 CO 3 and bestowing an ultra-long-term stability of 1087 cycles (4348 h). Taking into account its simplicity, scalable character and outstanding performance, this hierarchical composite electrode paves an effective trajectory for the future development of highly efficient cathodes for durable metal-CO 2 batteries. [Display omitted] • Excellent hierarchical structure of MXene and MnO 2 on carbon paper was fabricated. • Enriched charge transfer occurred on MXene and the MnO 2 by OH⋯O hydrogen bonding. • The prepared batteries showed an ultra-long cycle lifetime and low overpotential. • The optimized electronic structure can improve the metallicity of Li 2 CO 3. • The accelerated decomposition of discharge products promoted CRR and CER kinetics. Lithium-CO 2 batteries are recognized as an essential strategy for efficient carbon sequestration and energy storage to achieve carbon neutrality. Their cycle-ability and polarization voltage, however, are hindered by high decomposition voltage (≈4.3–4.5 V) of insulating Li 2 CO 3. Herein, we report a significant advance toward the rational design of self-supporting and ultra-long cycle lifetime cathode for Li-CO 2 batteries, dependence on a favorable hierarchical architecture and rich charge transfer constructed by homogeneously distributed MnO 2 nanoplates rooted in the MXene surface supported by carbon paper. Detailedly, it exhibits impressive ultra-long-term stability of 1087 cycles (4348 h) with a low polarization gap (≈ 0.47 V) at a high current of 200 μA cm−2, which is outperformed by all the liquid electrolyte-based Li-CO2 batteries reported previously. Electronic structure analysis reveals that facile charge transfer occurs between catalytic surface and Li 2 CO 3 , springing from the –OH functional group (in MXene) to MnO 2 by –OH⋯O hydrogen bonds, which acts as charge transfer channels, improving the metallicity of Li 2 CO 3 and facilitating its decomposition and extending battery cyclability. This work paves an effective trajectory for the future development of highly efficient cathodes for durable metal-CO 2 batteries. [ABSTRACT FROM AUTHOR]

Context: This research paper investigates the properties and potential applications of antiperovskite materials. Antiperovskites are a class of materials with a unique crystal structure, where the central atom is surrounded by a cage of anions. We review recent research on antiperovskite-based materials for energy storage, photovoltaics, catalysis, and sensors. We discovered that these materials display direct band gap semiconductors, strong absorption in the visible (VIS), ultra-violet (UV), and near infrared regions (NIR) based on their fundamental features, which is the most admirable quality that may be found in many optoelectronic devices. Both mechanical and thermodynamic stability have been confirmed for these materials. We discovered that these materials exhibit high figures of merit through the calculation of transport properties, which makes them a promising candidate for thermoelectric devices. It is anticipated that the proposed material BiPMg3, which has a theoretical efficiency of 11.5%, will make a suitable photovoltaic absorber. This paper highlights the potential of these materials for future technological advancements. Methods: Herein, we have used most authentic techniques to compute fundamental physical properties of these antiperovskites. Full-potential linear augmented plane wave (FP-LAPW) method has been used to investigate electronic, magnetic, optical properties, and make antiperovskites attractive for a variety of applications. In light of its implementation, we have checked the theoretical power conversion efficiency by first principles spectroscopic screening methodology, and inspect the fundamental physical parameters of antiperovskites, focusing on their potential as functional materials for energy and information technologies. [ABSTRACT FROM AUTHOR]

The as-prepared NCMOF/expanded graphite paper (NCMOF/EGP) exhibits high specific capacitance of 2.41 F cm−2 at 0.5 A cm−2, and still retain the specific capacitance of 1.75 F cm−2 even at 20 A cm−2, indicating the excellent rate capability. • NiCo-MOF/EGP composite has three-dimensional hierarchical structure. • NiCo-MOF/EGP electrodes have a high capacitance of 2.41 F cm−2 at 0.5 A cm−2. • The supercapacitor show high energy density of 0.11 mW h cm−2. • The capacitance retention of supercapacitor device is 71.2% after 10,000 cycles. Metal-organic frameworks (MOFs) are considered as a promising energy storage material owing to their inherent advantages of large surface area, regulatable pore size and functional groups. However, the relative poor electronic conductivity is an obstacle to their wide practical application. Herein, the partially-exfoliated graphite paper (EGP) composed of graphene nanosheets is prepared by a controlled cathodic exfoliation. EGP exhibits 3D hierarchical porous structure and good electronic conductivity, which acts as an ideal substrate for growing accordion-like structure NiCo-based bimetal-organic framework (NCMOF). The as-synthesized NCMOF/EGP shows high areal specific capacitance of 2.41 F cm−2 at 0.5 mA cm−2, and good rate performance of 72.6% at the current densities from 0.5 to 20 mA cm−2. Furthermore, the constructed NCMOF/EGP//active carbon delivers an energy density of 0.11 mW h cm−2 at a power density of 0.75 mW cm−2, and long cycle life. The outstanding electrochemical energy storage performance of NCMOF/EGP are assigned to 3D hierarchical porous structure and good electronic conductivity of EGP combined with layered structure of NCMOF. [ABSTRACT FROM AUTHOR]

The monoclinic semiconductor GeP is a new class of Group IV–V layered material, and it shows attractive anisotropic optical and electronic properties. In this paper, we investigate the structural and electronic evolution of layered GeP under pressure, using in situ x-ray diffraction, Raman and infrared spectra, and the density functional theory. All characterization methods reveal that the pressure causes two obvious phase changes. One isostructural transition is observed around 6 GPa. Above 21 GPa, another crystalline-to-amorphous transformation is obtained. It is worth noting that the high-pressure amorphous state can be retained at ambient conditions after the pressure is released. In addition, the pressure-induced red-shift of absorbance edge suggests its bandgap decreases with pressure. This result indicates that pressure has a significant effect on GeP. Meanwhile, it also provides a method for obtaining amorphous GeP, which is of interest to the energy storage community as it is a potential anode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Lithium-sulfur batteries are anticipated to be the next generation of energy storage devices because of their high theoretical specific capacity. However, the polysulfide shuttle effect of lithium-sulfur batteries restricts their commercial application. The fundamental reason for this is the sluggish reaction kinetics between polysulfide and lithium sulfide, which causes soluble polysulfide to dissolve into the electrolyte, leading to a shuttle effect and a difficult conversion reaction. Catalytic conversion is considered to be a promising strategy to alleviate the shuttle effect. In this paper, a CoS2-CoSe2 heterostructure with high conductivity and catalytic performance was prepared by in situ sulfurization of CoSe2 nanoribbon. By optimizing the coordination environment and electronic structure of Co, a highly efficient CoS2-CoSe2 catalyst was obtained, to promote the conversion of lithium polysulfides to lithium sulfide. By using the modified separator with CoS2-CoSe2 and graphene, the battery exhibited excellent rate and cycle performance. The capacity remained at 721 mAh g−1 after 350 cycles, at a current density of 0.5 C. This work provides an effective strategy to enhance the catalytic performance of two-dimensional transition-metal selenides by heterostructure engineering. [ABSTRACT FROM AUTHOR]

[Display omitted] • Coordination chemistry of transition metal hexacyanometallates. • Electronic structure of transition metal hexacyanometallates. • Structural diversity of transition metal hexacyanometallates. • Functional properties of transition metal hexacyanometallates. • Coordination controlled dimensionality in transition metal hexacyanometallates. The coordination chemistry of transition metal hexacyanometallates is a field of continuous advances and emerging applications. In the last three decades, relevant progress has been achieved on the understanding of the crystal and electronic structures of these materials, including those compositions resulting from non-conventional preparative routes. In this review, we summarize such advances at the time that provide a comprehensive overview of the structure-properties relationship. Since an improvement of the functionality of a given material is facilitated when its crystal and electronic structures are known, we provide guidelines on how to understand and predict the properties of these coordination polymers. In this family of materials, the extended 3D framework is usually formed by interconnected ⋅⋅⋅-T-N≡C-M-C≡N-T-⋅⋅⋅ chains. When these chains have a linear geometry, the formed solids crystallize either with a cubic or pseudocubic unit cell, and these coordination polymers are known as Prussian blue analogs. In the last years, deviations from such regularity have been observed for an increasing number of T metals, where the N end of the CN– ligand forms a bifurcated coordination bonding with two T metal centers. Other less common coordination modes at the N end have been also documented and are herein considered. Since the first documented report on this family of coordination polymers (in 1704), a search of published documents, using Science Finder and Google Scholar under the keywords of Prussian blue and transition metal hexacyanometallates, produces above four thousand outputs, mainly scientific papers. But these papers mostly deal with potential applications, and only a small fraction of them includes structural studies in the context of coordination chemistry. This review is structured in three blocks of sections. Initially, the crystal and electronic structures are discussed, then, the related physical properties are analyzed, and finally, their implications on the applications, with the focus on the structure-properties relationship are discussed. The accompanying Supplementary Data file has been conceived as a source of useful structural information, which together with the main document will help the readers to understand better these compounds and devise new and promising applications. [ABSTRACT FROM AUTHOR]

• Systematic study of 3d transition metal-doped CNTs. • V(Cr, Mn, Co)-doped CNTs show spin-polarization effects. • The 3d transition metal doping makes a big difference to the energy band. • 3d transition metal doping increases the quantum capacitance. • Ni-CNT has the largest quantum capacitance near zero potential. Supercapacitors are valued as one of the new green energy storage devices, but the low energy density limits the wide application of supercapacitors. In this paper, the effects of 3d transition metal doped on electronic structure and quantum capacitance of carbon nanotubes are investigated using DFT. The calculations show that elemental doping has caused the break-up of two degenerate states near the Fermi level, quasi-local state changes in the energy band, and the creation of new energy bands. The doping of V(Cr, Mn, Co) causes spin polarization in the energy band. The change in energy band affects the density of states near the Fermi level, effectively increasing the quantum capacitance and surface charge density of the carbon nanotube electrode. The quantum capacitance of Ni-doped carbon nanotubes is the largest, at 59.74 µF/cm2. In the range of water stability, Ti(V, Gr, Mn, Co)-CNT are suitable for use as electrode materials in symmetrical double layer supercapacitors. Sc(Fe, Cu, Zn)-CNT is suitable for use as anode materials in asymmetric double layer supercapacitors. Ni-CNT is suitable for use as a cathode material for asymmetric double layer supercapacitors. This study verifies the feasibility of 3d transition metal doping to improve the quantum capacitance of carbon nanotube electrodes. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper is concerned with calculating the optimum rating for two dynamic voltage restorers (DVRs) when used in an interline DVR (IDVR) structure. An IDVR consists of two or more DVRs which have a common dc link and, thus, can exchange active power. This can increase the compensation range of an IDVR compared with separate but otherwise similar DVRs. The basic operation of the DVR and IDVR is briefly explained. The limitations of IDVR operation in terms of active power exchange are explained and, based on that, the expressions governing the steady-state operation of IDVR are derived. The compensation range of an IDVR is compared with that of two separate DVRs. This paper also explores how the limitations in absorbing power from a healthy feeder can narrow the compensation range of an IDVR. After identifying and formulating various limitations in IDVR operation, a design procedure is presented to determine the optimum size (or rating) of the DVRs in an IDVR structure. In the proposed approach, all possible scenarios concerning healthy and faulty feeders are taken into consideration. Examples along with graphs and tables aid in conveying the proposed approach. [ABSTRACT FROM AUTHOR]

As the number of wind power applications with power electronic interfaces in the grid increases, it is becoming unacceptable to disconnect the generating units every time disturbances occur, especially under voltage dips, as was a common practice in the past. Keeping the converter online during unbalanced voltage, and guaranteeing the actual standards of the converter connected to the grid, is becoming a very critical issue. From these goals, the design of a robust back-to-back neutral point clamped (three levels) voltage source converter of 150 kVA is developed in this paper. The converter is divided into two main parts: the power electronic system and the control electronic system. Concerning the first part, on the one hand, the paper presents the designs of active and passive components as insulated gate bipolar transistor, free-wheeling diodes, clamping diodes, grid filter, dc-bus capacitors, etc.; and on the other hand, the converter requirements are analyzed to ride through real grid conditions, i.e., unbalanced voltage dips. Concerning the control electronic system, the chosen electronic structure and the task distribution between the two processors used are shown. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the variations in the properties, characteristics and hydrogenation energy barriers of magnesium clusters induced by titanium. DFT approach was used to determine the most stable structures at this theory level and then MP2 was used to refine the energy calculations with the basis set 6-311g(d) for magnesium and hydrogen, and pseudopotential lanl2dz for titanium. Bimetallic clusters showed higher stability and reactivity than the corresponding magnesium ones. Titanium induces a change in the magnesium atoms in their electronic configuration reflected in an increase of the population of their orbitals. At the same time titanium electronic populations is modified. These changes cause variations in some reactivity parameters such as the Fukui indexes which modify the hydrogenation of the magnesium clusters and bimetallic clusters. For example, there is a reduction in the energy barrier for dissociation of the H2 molecule in the bimetallic clusters. In the hydrogenated cluster the hydrogen atoms form bridges between all of the magnesium or magnesium–titanium atoms. These results indicate that, energetically, bimetallic systems can be more promising systems for hydrogen storage. [Copyright &y& Elsevier]

Abstract: A constant value of the activation energy of direct current conductivity in chalcogenide glassy semiconductors is a strong evidence of the existence of negative-U centers in these materials. Multiphonon tunnel ionization of negative-U centers in strong electric fields is the cause of current–voltage characteristic nonlinearity. Taking into account the Joule heating allows to obtain electronic–thermal instability and then form an S-shaped current–voltage characteristic. The model described in this paper is in good agreement with the available experimental data on chalcogenide glassy semiconductors. [Copyright &y& Elsevier]

The obtained Co-Mo-N@Ag electrode exhibited outstanding electrocatalytic performance and distinguished durability for water splitting in 1 M KOH electrolyte. [Display omitted] • Co-Mo-N@Ag catalyst with heterogeneous interface structure were synthesized. • Co-Mo-N@Ag exhibited excellent electronic structure and interface synergy effect. • Heterogeneous interface is contributed to the enhancement of catalytic activity. Designing highly active and robust bifunctional electrocatalysts toward efficient overall water splitting using for novel renewable energy storage and conversion systems is still a challenging task. Here, self-supported bimetallic cobalt-molybdenum nitride with silver nanoparticles decoration (Co-Mo-N@Ag) growth in situ on carbon paper was rationally designed and fabricated for overall water splitting in alkaline media. By virtue of the admirable compositional and structural advantages of exposed enough active sites, regulated favorable electronic structure, and engineered powerful interface synergy effect, the Co-Mo-N@Ag electrode exhibits superior electrocatalytic performance in 1 M KOH. In the details, an excellent oxygen evolution reaction (OER) activity with an extremely low overpotential of 234 mV at 10 mA cm−2 and a small Tafel slope of 54 mV dec-1, as well as a remarkable hydrogen evolution reaction (HER) activity with a low overpotential of 90 mV at 10 mA cm−2 and Tafel slope of 73 mV dec-1 were acquired by Co-Mo-N@Ag. As a result, it takes a low voltage of 1.56 V to reach 10 mA cm−2 in alkaline overall water splitting. This work presents the heterogeneous interfacial structure decorated by silver and provides a feasible method to increase the OER and HER activity of metal nitrides. [ABSTRACT FROM AUTHOR]

Conductive CoS 2 and cycling stable MoS 2 are integrated to form the interconnected CoS 2 /MoS 2 nanosheet composite with electroactive interface grown on Mo foil substrate to act as high-performance supercapacitor anode material with electrochemical and mechanical stability. The band gap and density of state of CoS 2 /MoS 2 determined by density functional theory simulation calculation indicates its improved electrical conductivity. The interface binding energy and differential charge density reveal that strong crystal interface interaction between MoS 2 (002) and CoS 2 (111) enables effective charge transfer in interconnected CoS 2 /MoS 2 nanosheet composite. CoS 2 /MoS 2 exhibits higher specific capacitance of 605.77 mF cm−2 than MoS 2 of 218.1 mF cm−2 at 1.0 mA cm−2 in 0.5 M Na 2 SO 4. The rate capacitance retention is improved from 57.8% of MoS 2 to 82.8% of CoS 2 /MoS 2 at 1–10 mA cm−2. The high cycling stability is achieved for MoS 2 (100.2%) and CoS 2 /MoS 2 (104.05%) after 5000 cycles at 10 mA cm−2 due to self-activation of multilayered MoS 2. An asymmetric solid-state supercapacitor using CoS 2 /MoS 2 anode and MnO 2 /carbon paper cathode achieves a capacitance of 4.32 F cm−3 at 1.0 mA cm−2 and an energy density of 1.944 mWh cm−3 at a power density of 18 mW cm−3, 97.8% after 5000 cycles at 5.0 mA cm−2, presenting effective energy storage. [ABSTRACT FROM AUTHOR]